单个警报消息javascript中的多种形式验证错误消息

Question

I am trying to achieve functionality of showing multiple validation error messages in single alert message.

i have three text fields, checking whether user entered a value or not in that text field. if user does not entered any value and tries to submit form, I have to show to the user that three field are mandatory.

piece of code as below :

function validateInput(ele, note, Name) 
{   
var val = ele.value;    
 if (val == '')
 {      
     note = note +Name+"element can not be Empty; \n";
     return false;
 }
return true;
}

function validateForm() {
var note =  "";
var ele1 = validateInput(document.getElementById('input1'), note, 'From');
var ele2 = validateInput(document.getElementById('input2'), note, 'To');
var ele3 = validateInput(document.getElementById('input3'), note, 'CC');
alert(note);
return (ele1 && ele2 && ele3);  
}

Answer 1

You could use an object to pass values by reference, but for this it isn't necessary. Try this:

function validateInput(ele, Name) 
{   
     var val = ele.value;        
     return val == '' ? note +Name+"element can not be Empty; \n" : "";
}

function validateForm() {
var note =  "";
note += validateInput(document.getElementById('input1'), 'From');
note += validateInput(document.getElementById('input2'), 'To');
note += validateInput(document.getElementById('input3'), 'CC');
var isValid = note == "";
if( !isValid )
    alert(note);
return isValid;  
}

Answer 2

Strings are not references to String object instance.

You should declare the note var in parent context:

var note = '';
function validateInput(ele, Name) 
{   
var val = ele.value;    
 if (val == '')
 {      
     note = note +Name+"element can not be Empty; \n";
     return false;
 }
return true;
}

function validateForm() {
note =  "";
var ele1 = validateInput(document.getElementById('input1'), 'From');
var ele2 = validateInput(document.getElementById('input2'), 'To');
var ele3 = validateInput(document.getElementById('input3'), 'CC');
alert(note);
return (ele1 && ele2 && ele3);  
}